cli: fix handling of scaling jobs which don't generate evals. (#20479)

In some cases, Nomad job scaling will not generate evaluations
such as parameterized jobs. This change fixes the CLI behaviour
in this case, and copies the job run command for consistency.

.changelog/20479.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+cli: Fix handling of scaling jobs which don't generate evals
+```

command/job_scale.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/hashicorp/nomad/api"
 	"github.com/mitchellh/cli"
@@ -127,13 +128,13 @@ func (j *JobScaleCommand) Run(args []string) int {
 	// Detail the job so we can perform addition checks before submitting the
 	// scaling request.
 	q := &api.QueryOptions{Namespace: namespace}
-	job, _, err := client.Jobs().ScaleStatus(jobID, q)
+	jobScaleStatusResp, _, err := client.Jobs().ScaleStatus(jobID, q)
 	if err != nil {
 		j.Ui.Error(fmt.Sprintf("Error querying job: %v", err))
 		return 1
 	}
 
-	if err := j.performGroupCheck(job.TaskGroups, &groupString); err != nil {
+	if err := j.performGroupCheck(jobScaleStatusResp.TaskGroups, &groupString); err != nil {
 		j.Ui.Error(err.Error())
 		return 1
 	}
@@ -155,9 +156,36 @@ func (j *JobScaleCommand) Run(args []string) int {
 			j.Colorize().Color(fmt.Sprintf("[bold][yellow]Job Warnings:\n%s[reset]\n", resp.Warnings)))
 	}
 
-	// If we are to detach, log the evaluation ID and exit.
-	if detach {
-		j.Ui.Output("Evaluation ID: " + resp.EvalID)
+	jobInfo, _, err := client.Jobs().Info(jobID, q)
+	if err != nil {
+		j.Ui.Error(fmt.Sprintf("Error looking up job: %s", err))
+		return 1
+	}
+
+	// Check if the job is periodic or is a parameterized job
+	isPeriodicJob := jobInfo.IsPeriodic()
+	isParameterizedJob := jobInfo.IsParameterized()
+	isMultiregionJob := jobInfo.IsMultiregion()
+
+	// Check if we should enter monitor mode
+	if detach || isPeriodicJob || isParameterizedJob || isMultiregionJob {
+		j.Ui.Output("Job scale successful")
+		if isPeriodicJob && !isParameterizedJob {
+			loc, err := jobInfo.Periodic.GetLocation()
+			if err == nil {
+				now := time.Now().In(loc)
+				next, err := jobInfo.Periodic.Next(now)
+				if err != nil {
+					j.Ui.Error(fmt.Sprintf("Error determining next launch time: %v", err))
+				} else {
+					j.Ui.Output(fmt.Sprintf("Approximate next launch time: %s (%s from now)",
+						formatTime(next), formatTimeDifference(now, next, time.Second)))
+				}
+			}
+		} else if !isParameterizedJob {
+			j.Ui.Output("Evaluation ID: " + resp.EvalID)
+		}
+
 		return 0
 	}
 
@@ -167,7 +195,7 @@ func (j *JobScaleCommand) Run(args []string) int {
 		length = fullId
 	}
 
-	// Create and monitor the evaluation.
+	// Detach was not specified, so start monitoring.
 	mon := newMonitor(j.Ui, client, length)
 	return mon.monitor(resp.EvalID)
 }

command/job_scale_test.go

@@ -130,6 +130,44 @@ func TestJobScaleCommand_MultiGroup(t *testing.T) {
 	}
 }
 
+func TestJobScaleCommand_Parameterized(t *testing.T) {
+	ci.Parallel(t)
+
+	srv, client, url := testServer(t, true, nil)
+	defer srv.Shutdown()
+	testutil.WaitForResult(func() (bool, error) {
+		nodes, _, err := client.Nodes().List(nil)
+		if err != nil {
+			return false, err
+		}
+		if len(nodes) == 0 {
+			return false, fmt.Errorf("missing node")
+		}
+		if _, ok := nodes[0].Drivers["mock_driver"]; !ok {
+			return false, fmt.Errorf("mock_driver not ready")
+		}
+		return true, nil
+	}, func(err error) {
+		t.Fatalf("err: %s", err)
+	})
+
+	ui := cli.NewMockUi()
+	cmd := &JobScaleCommand{Meta: Meta{Ui: ui}}
+
+	// Create and register a parameterized job. The parent jobs do not create
+	// evaluations, even when scaled.
+	job := testJob("parameterized_job")
+	job.ParameterizedJob = &api.ParameterizedJobConfig{}
+
+	_, _, err := client.Jobs().Register(job, nil)
+	must.NoError(t, err)
+
+	// Scale the parent job and ensure the output matches what we expect.
+	code := cmd.Run([]string{"-address=" + url, "parameterized_job", "2"})
+	must.Eq(t, 0, code)
+	must.StrContains(t, ui.OutputWriter.String(), "Job scale successful")
+}
+
 func TestJobScaleCommand_ACL(t *testing.T) {
 	ci.Parallel(t)
 
@@ -175,7 +213,7 @@ namespace "default" {
 	capabilities = ["read-job-scaling", "scale-job"]
 }
 `,
-			expectedErr: "No evaluation with id",
+			expectedErr: "Error looking up job",
 		},
 		{
 			name: "read-job-scaling and submit-job allowed but can't monitor eval without read-job",
@@ -184,7 +222,7 @@ namespace "default" {
 	capabilities = ["read-job-scaling", "submit-job"]
 }
 `,
-			expectedErr: "No evaluation with id",
+			expectedErr: "Error looking up job",
 		},
 		{
 			name: "read-job-scaling and scale-job allowed and can monitor eval with read-job",
@@ -220,7 +258,7 @@ namespace "default" {
 	capabilities = ["read-job-scaling", "scale-job", "list-jobs"]
 }
 `,
-			expectedErr: "No evaluation with id",
+			expectedErr: "Error looking up job",
 		},
 		{
 			name:      "job prefix works with list-job and can monitor eval with read-job",